Railway traffic controlling system



June 27, 1939. w. K. HOWE RAILWAY TRAFFIC CONTROLLING SYSTEM Filed June 16, 1937 flow, 4a @412 ATTORNEY INVENTOR 1U. 7U.

llllllll L Ir x 51 3 u nHTiog o s 2n IN 13 m o fl Patented June 27, 1939 UNITED STATE TEN? OFFICE RAILWAY TRAFFIC CONTROLLING SYSTEM Application June 16, 1937, Serial No. 148,448

3 Claims.

This invention relates to centralized trafiic controlling systems for railroads, and more particularly pertains to a system employing direct line wire control for the switches and signals.

The present invention provides for the control of a track switch over one polarized control circuit, while its governing signals are controlled over another polarized control circuit. The switch control polarized circuit includes a polarneutral relay at the track switch so arranged that the polar contacts govern the position to which the track switch is operated while the neutral contacts are efiective at times to prevent operation of the track switch. Likewise, the control 15 circuit for governing the signals is supplied with a polar-neutral relay having polar contacts to govern the direction in which signals shall clear and having neutral contacts to determine whether the signals shall be at clear or at stop.

20 The present invention so interrelates the switch and signal control circuits that the manual act for clearing a signal prevents further manual control of a switch machine although provision is made that an operation of a track switch 25 initiated before such manual act to clear the signal shall be completed.

It is further provided in accordance with the present invention that the switch machine for operating the track switch shall be of the type 30 which has what is termed an electrical bias control that is, if for one reason or another the track switch becomes unlocked or to a position out of correspondence with its polar-neutral control relay, it will automatically be energized 35 so as to operate back to a position in correspondence with such control relay. This bias is effective under all conditions except when the polar-neutral switch control relay is deenergized. This arrangement provides that the operator may 40 remove energy from the polar-neutral control relay and thereby allow the track switch to be locally hand operated to a new position without any danger of its being returned to its former position by the jarring of the local contactor 5 While a train is being hand-signalled over the track switch.

The present invention also provides the above features in combination with what has been conveniently termed the electric lock equivalent.

50 In other words, the control lever for governing the operation of the track switch must be in correspondence with the position of the track switch after the signals have been returned to stop in order that the operator may effect the operation 55 of the track switch to a new position.

Other objects, purposes and characteristic features of the present invention will be in part obvious from the accompanying drawing and in part pointed out as the description of the invention progresses.

In describing the invention in detail, reference will be made to the accompanying drawing which is a diagrammatic illustration of one embodiment of the present invention as applied to the control of traffic over a single railroad track 1 switch.

Although the traffic controlling system of the present invention may be applied to various track layouts involving conflicting routes and nonconflicting routes as well as other various conditions encountered in interlocking practice, it has been specifically illustrated in the present embodiment as applied to a single track switch with its signals, which switch and signals are contemplated as associated with an automatic block signal system of some suitable type such as disclosed, for example, in the prior patent of S. N. Wight, Pat. No. 2,082,436, dated June 1, 1937.

With reference to the accompanying drawing,

a rail road track switch TS is illustrated as connecting the rails 3 or" a main track to the rails 4 of a turn-out or diverging track. This track switch TS is operated by a power driven switch machine SM which may be of any suitable type, such for example, as disclosed in my Patent No. 1,465,903, dated September 4, 1923, with the control of the motor of such switch machine being provided in any suitable way, but, which, for convenience, has been assumed to be of the type of control shown in the Patent No. 1,877,876, dated September 20, 1932, granted to W. H. Hoppe et a1.

My prior Patent 1,466,903 shows how such a switch machine SM may be hand cranked, and when such local operation is in progress, a contact, included in the motor operating circuit, is opened. For convenience in the present disclosure, the details of such wiring of the switch machine has not been shown, but it is to be understood that the switch machine SM includes a polar relay such as relay CR. in the Patent No. 1,877,876 for controlling, through suitable contactors, the energy supplied to the armature and field winding of the motor, and that suchoperating circuit of the motor includes a contactor MC which is opened when the switch machine is manually cranked. Although the details of such control have not been shown, it is believed that with this brief description the features of the present invention will be readily understood.

The control relay CR (not shown) is controlled in accordance with the present invention as specifically shown in the drawing.

The main track adjacent the track switch TS and a portion of the diverging track to the fouling point comprises a detector track circuit of the closed circuit type with the usual track battery 5 and track relay T, which detector track circuit is insulated from the rest of the track by the usual insulated joints.

Trafiic over the track switch in an east bound direction is governed by signals IA and HB over the main track and over the diverging track respectively; while signals 2A and 2B are provided for governing trafiic in a west bound direction on the main track and ofi the diverging track respectively.

Associated with the signal I is home relay IAH of the usual polar-neutral type, similarly associated with the signal IB is a home relay IBH of the polar-neutral type. These relays lAH and !BH are governed. in accordance with traffic in advance of the signals EA and IE on the main track and on the diverging track respectively. Likewise, associated with signals 2A and 2B is the home relay 2H of the usual polar-neutral type which relay 21-1 is governed in accordance with the traffic conditions in advance of the signals 2A and 213 on the main track. The control of these home relays has not been illustrated in. detail as such control is well known to those skilled in the art and has been shown in the above mentioned patent of S. N. Wight, Pat. No. 2,082,436, dated June 1, 1937.

The track switch TS and switch machine SM are preferably provided with a point detector contact mechanism of some suitable type, such, for example, as shown in the patent to C. S. Bushnell, Pat. No. 1,517,236, dated November 25, 1924. These point detector contacts are employed to energize a switch position relay WP of the usual polar-neutral type with one polarity when the track switch is in one extreme locked position and with the opposite polarity when the track switch is in the opposite locked position or to deenergize this relay WP whenever the track switch is unlocked or is in operation. Such control of a relay WP is well known in the art and has merely been indicated in the present disclosure by a dotted line extending from the relay WP to the track switch TS and the switch machine SM.

A polar-neutral relay WZ, having a polar armature of the magnetic stick type, is provided to govern the switch machine SM in accordance with local signalling conditions while a polarneutral relay Z is controlled over a line wire 58 in accordance with the manual operation of a switch machine control leve'r SML located in a central control oflice.

A polar neutral relay GZ is governed from the central control office over another line wire 5| for controlling the operation of the signals by selecting in cooperation with the normal and reverse correspondence relays NCR and RCR the proper one of four signal control relays G, such as relays lAG, iBG, ZAG, and 23G. As obvious from the preceding numerals applied to the relay G, these relays are provided to control the respective signals IA, lB, 2A and 2B, which signals have been illustrated as being of the color-light type. These signals preferably display red or danger indications whenever the corresponding relays G are deenergized and display yellow or green indications whenever such relays G are energized, providing the traflic conditions, as indicated by their respective relays lAH, lBH and 2H, are such that it is safe for traffic to proceed. Although the control of the signals has been in part illustrated and in part indicated, it is to be understood that such control may include various other features so as to make the signals conventional stick signals, signals illuminated only upon the approach of a train, or signals having some other well known feature without departing from the scope of the present invention.

Associated with the relays lAG, lBG, ZAG and ZBG is a signal at stop relay M which is energized only when all of the G relays governing trafic over the track switch TS are deenergized. In other words, the relay M indicates the condition of the signals and is energized only when all signals governing routes over the track switch are at stop.

Associated with the signal control relay (EZ and the switch control relays Z and WZ. is a suitable lock relay L of the usual neutral type. This lock relay L is normally energized, but is deenergized whenever the signal control relay GZ is energized, the track relay T is deenergized. or the signals at stop relay M is deenergized. Although the control of this look relay L has been limited to the disclosure of the features more directly related to the present invention, it is to be understood that it may have associated therewith other circuit arrangements to provide the usual approach looking for a track switch wii h time release means, and the like.

Relays NCR and RCR are associated with the relays WZ and WP in a manner that the relay NCR is energized whenever the track switch TS is in a normal extreme locked position in correspondence with the relay WZ, and in a manner that the relay RCR is energized whenever a track switch TS is in a reverse extreme lock position in correspondence with the relay WZ.

In the central office, a suitable control machine is provided with the usual miniature track diagram and suitable control levers and indicators advantageously located thereon. For convenience in describing the present invention, only the switch machine control lever SML and the signal control lever SGL have been shown. The switch machine lever SML is preferably of three-position type having a contact 5 which may be operated to either of three positions in any one of which it remains until operated to a dif" ferent position. Similarly, the signal control lever SGL has a contact 35 which is also operable to either of three positions, in any one of which it remains until operated. to a new position.

For the purpose of simplifying the illustration and facilitating in the explanation various parts and circuits constituting the embodiment; of the invention have been shown diagrammatically and certain conventional illustrations have been em" ployed. Also, symbols are used to indicate connections to the terminals of suitable batteries or other sources of electrical current instead of showing all the wiring connections to these terminals.

The symbols and are employed to indicate the positive and negative terminals respectively of suitable batteries, or other sources of direct current, and the circuits with which these symbols are used always have current flowing in the same direction. The symbols 3+) and (B-) indicate connections to the opposite terminals of a suitable battery, or other direct source, which has a central or intermediate tap designated (CN), and the circuits with which these symbols are used may have current flowing inone direction or the other depending upon the particular terminal used in combination with the intermediate tap (CN). It is further understood that in the event alternating current is used, the symbols may then be considered as indicating merely the relative instantaneous polarities.

It is believed that the present invention will be best understood by further description setting forth the characteristic features and functions of the system from the standpoint of typical operations under certain typical conditions, although it is to be understood that various conditions of operation may arise and be inherent in the embodiment of the present invention that are not specifically described in detail.

OPERATION Normal conditions.--With the detector track section associated with the track switch TS unoccupied by a train and with the control levers SML and SGL in the positions shown, the various devices, relays and circuits assume positions and conditions of energization illustrated. The track relay T is, of course, normally energized.

With the signal lever SGL in a central or stop position, the relays |AG--IBG and 2AGZBG are deenergized which closes a circuit for the signals at stop relay M from through a circuit including back contact 29 of relay 2AG, back contact 30 of relay ZBG, back contact 3| of relay IAG, back contact 32 of relay IBG, windings of relay M, to

With the relays T and M energized and the relay GZ deenergized, an energizing circuit is closed for the lock relay L from through a circuit including back contact l2 of relay GZ, front contact l3 of relay M, front contact [4 of relay T, polar contact l5 of relay WP in a right hand position, polar contact iii of relay Z in a right hand position, front contact I! of relay Z, windings of relay L, to

It is, of course, apparent that if the switch machine control lever SML were in the opposite or reverse position, the polar contact Iii of relay Z would be in a left hand position, and assuming that the track switch TS had followed such control, the polar contact l5 of relay WP would also be in a left hand position closing a circuit from i through back contact l2 of relay GZ, front contact 13 of relay M, front contact I4 of relay T, polar contact 15 of relay WP in a left hand position, polar contact l6 of relay Z in a left hand position, front contact ll of relay Z, windings of relay L, to

Whenever the lock relay L is picked up, its stick contact I8 shunts out the contacts of the relay Z and the relay WP.

The normal energizing circuit for the relay WZ is closed from (B+), through a circuit including polar contact I of relay Z in a right hand posi tion, front contact 8 of relay Z, front contact 9 of relay L, windings of relay WZ, to (ON). The reverse energizing circuit for the relay WZ is closed when relay Z is energized with negative energy by lever SML in a reverse position from (B), through a circuit including polar contact I of relay Z in, a left hand position, front contact 8 of relay Z, front contact 9 of relay L, windings of relay WZ, to (ON).

The relay WP repeats the normal locked position of the track switch TS, which in correspondence with relay WZ in a normal position closes an energizing circuit for the normal correspondence relay NOR from through a circuit ineluding polar contact 28 of relay WP in a right hand position, front contact 2! of relay WP, front contact 26 of relay WZ, polar contact 25 of relay WZ in a right hand position, windings of relay NOR, to

When the track switch TS is in a reverse locked position in correspondence with the relay WZ in a reverse position, the correspondence relay RCR is energized by a circuit closed from through a circuit including polar contact 25 of relay WZ in a left hand position, front contact 26 of relay WZ, front contact 21 of relay WP, polar contact 28 of relay WP in a left hand position, windings of relay RCR, to

All of the signals are at stop by reason of the respective contacts 33, 34, 35 and 36 of relays IBG, ZBG, IAG and ZAG being in dropped away positions.

Manual control of the track switch.-Let us assume that the operator moves the switch machine control lever SML from its normal position to its reverse position. This applies negative potential from (B) through contact 6 over the line wire 59 to the relay Z in the field. Such reversal of polarity on the relay Z causes its polar contacts to be operated to left hand positions and its neutral contacts to be momentarily dropped during such operation and returned to picked up positions. However, the momentary opening of front contact ll does not drop the relay L because the stick contact !8 shunts contacts l5, l5 and I1 in the pick up circuit for the relay L, as above pointed out. Thus, the reversal of energy on the relay Z causes the reversal of energy on the relay WZ over the circuit above pointed out. As soon as the relay WZ operates its polar contacts to the left, the relay NCR is deenergized, so that an energizing circuit for the switch machine SM is closed from through a circuit including back contact 24 of relay NCR, hack contact 23 of relay RCR, polar contact 2i of relay WZ in a left hand position, front contact 22 of relay WZ, through the master control relay of the switch machine SM, front contact IQ of relay WZ, polar contact 2!) of relay WZ in a left hand position, to This energization of the switch machine SM causes it to operate the track switch TS from a normal locked position to a reverse locked position.

While the track switch TS is in midstroke or in operation the relay WP is, of course, deenergized, but when it reaches its reverse position, the polar contacts of the relay WP are actuated to the left and its neutral contacts pick up. Such operation causes the relay RCR to be energized through its circuit previously pointed out, which opens back contact 23 removing energy from the switch machine SM.

It will be evident that the lock relay L remains energized through its stick circuit during such operation so that the relay WZ can be restored to its normal energized position upon reversal of the switch machine control lever SML any time during. the operation of the switch machine. In other Words, the circuit arrangements provide for the change in direction of operation of the switch machine SM while in midstroke.

It will, of course, be understood that the return of the switch machine lever 'SML from a reverse position to a normal position applies positive potential (B+) to the line wire 50 and causes the relay Z to actuate its polar contacts to the right and to pick up its neutral contacts, which also applies positive potential from (B+) to the relay WZ.

The reversal of the relay WZ drops the correspondence relay RCR and applies energy to the switch machine SM from through a circuit including back contact 24 of relay NOR, back contact 23 of relay RCR, polar contact 20 of relay WZ in a right hand position, front contact I9 of relay WZ, through the switch machine master relay, front contact 22 of relay VIZ, polar contact 2| of relay WZ in a right hand position, to

This energization of the switch machine SM causes the track switch TS to be operated back to its normal position in which the relay WP corresponds with the position of the relay WZ so that the relay NCR is again energized, opening back contact 24 and deenergizing the switch machine SM.

Signal controL-When the track switch TS is in a normal position, the operator may operate the signal control lever SGL to the right for clearing the signal IA; or operate the lever SGL to the left for clearing the signal 2A.

The operation of the signal lever SGL to the right closes the contact 45 in a left hand position to apply positive potential from (3+) to the line wire 5| energizing the relay G2. The opening of back contact I2 of relay GZ deenergizes the lock relay L, so that back contact 38 of relay L is closed, thereby closing an energizing circuit for the relay |AG from through a circuit including front contact 31 of relay T, back contact 38 of relay L, front contact 39 of relay GZ, polar contact Q0 of relay GZ in a right hand position, front contact 42 of relay NCR, windings of relay lAG, to

The picking up of the relay IAG opens its back contact 3| deenergizing the relay M which, in turn, opens front contact l3 so as to maintain the relay L deenergized so long as the signal is cleared. The operation of contact 35 of the relay IAG from a back point to a front point clears the signal IA so that trafi'lc may pass over the track switch TS.

On the other hand, if the lever SGL is operated to the left, the contact 2-5 is closed in a right hand position so that negative potential (B) is applied to the line wire 5| energizing the relay G2 with negative potential. Similarly, such energization opens back contact |2 deenergizing the lock relay L and completes an energizing circuit for the relay ZAG from through a circuit including front contact 31 of relay '1, back contact 38 of relay L, front contact 39 of relay GZ, polar contact 40 of relay GZ in a left hand position, front contact 44 of relay NCR, windings of relay ZAG, to

The picking up of contact 33 of the relay BAG causes the indication of the signal 2A to be changed from stop to clear. Also, the opening of back contact 29 of relay ZAG deenergizes the relay M, opening front contact l3 which maintains the lock relay L deenergized so long as the signal is clear.

Assuming the track switch TS to be in a reverse position, the operation of the signal lever SGL to a right hand position and the application of positive potential to the relay GZ causes the signal IE to be cleared. Under such circumstances the relay RCR is energized instead of the relay NCR, so that upon the energization of the relay GZ and the dropping of the lock relay L by opening back contact l2, an energizing circuit is closed for the relay EBG from (-1-), through a circuit including front contact 3? of relay '1, back contact 38 of relay L, front contact 39 of relay GZ, polar contact 18 of relay GZ in a right hand position, front contact 4| of relay RCR, windings of relay IBG, to

On the other hand, when the track switch TS is in a reverse position and the lever SGL is operated to the left to apply negative potential to the relay GZ, an energizing circuit is closed for the relay ZBG upon the dropping of the lock relay L by the opening of back contact I2. This circuit is closed from through a circuit including front contact 31 of relay T, back contact 38 of relay L, front contact 39 of relay GZ, polar contact M! of relay GZ in a left hand position, front contact 43 of relay RCR, windings of relay ZBG, to

The picking up of the contact 34 changes the indication of the signal 2B from step to clear. The opening of back contact 30 of relay 213G deenergizes the relay M so that the relay L is maintained deenergized so long as the signal is clear.

It is, of course, to be understood that the return to a central or at stop position of the signal lever SGL is effective, in each of the four cases above explained, to return the particular signal then cleared to stop. This is because the relay GZ opens the energizing circuit of its particular signal relay such as IAG at front contact 39. Such return to stop of a signal causes the relay M to be energized and the relay L to be picked up providing the relays Z and WP are in correspondence, which will be described in detail under consideration of the lever lock equivalent" feature of the present invention.

Checking the response of relay WZ.As above described, the relay L is deenergized each time the relay GZ is energized to clear a signal, and when thus deenergized opens the pick up circuits for the relay WZ so that it can not be controlled by the relay Z. However, the relay WZ is maintained energized under such circumstances by a stick circuit. The normal stick circuit is closed from (13+), through a circuit including polar contact l! in a right hand position, front contact l0 of relay WZ, back contact 9 of relay L, windings of relay WZ, to (CN).

The reverse stick circuit is closed from (3*), through a circuit including polar contact ll of relay WZ in a left hand position, front contact Ill of relay WZ, back contact 9 of relay L, windings of relay WZ, to (CN).

It is apparent in each case that the stick circuit upon which the relay WZ is dependent has the same polarity of energy applied thereto that has been applied through its pick up circuit by the relay Z. If for one reason or another the polar contacts of the relay WZ should fail to respond to the energy applied to its pick up circuits, then upon the dropping of the lock relay L and the closure of back contact 9 an opposite polarity would be applied to the relay WZ by reason of the polar contact ll of the relay WZ being in the wrong position. Such reversal of energy upon the relay WZ would cause the magnetic flux in the relay to reverse in direction and in so doing to pass through zero. When the magnetism of the relay WZ passes through zero, the neutral armature of the relay WZ drops away and causes the opening of contact I0 thereby opening the stick circuit of the relay WZ and causing it to remain deenergized.

When the relay WZ is deenergized, the relays NCR and RCR cannot be energized by reason of open front contact 26. Thus, a signal cannot be cleared unless the polar contacts of the relay WZ have properly responded to the polarity of energy applied to its pick up circuits.

Hand signalling over the track switch.There are certain conditions that arise in an interlocking plant where it becomes necessary for the operator in the tower to permit a trainman to hand crank a track switch TS from one position to another and then signal to the train toproceed over the track switch subject to hand signal rules. Under such conditions, it is absolutely necessary that during the passage of a train over the track switch, no energy shall be applied thereto and cause the unintended operation of said track switch back to its former position and thereby split or derail a train.

The present invention provides that the tower operator may move the switch machine control lever SML to a mid or central position whenever it is desired toallow a trainman to manually operate the track switch and locally direct the passage of traffic thereover. Such movement of the lever SML to a mid position removes all energy from the relay Z which, in turn, opens front contact 8, removing energy from the relay WZ, so that the relay WZ becomes deenergized, opening front contacts I!) and 22. This removes energy from the switch machine SM and shunts its control wires so that it can not receive energy due to the jarring closed of a contact in the switch machine or any other reason local thereto. The back contacts 9 and 22 so shunt the control wires of the switch machine SM that the possibility of a cross connection of power causing an accidental and erroneous operation of the switch machine is eliminated.

When the trainman inserts the hand crank to manually actuate the track switch TS to an opposite position, such insertion of the crank opens a contact MC by removing the movable element 46 from between stationary contacts thereby opening the motor circuit itself. This is to protect the trainman who is hand cranking the switch machine. When the track switch TS- has been moved to a new position, the trainman removes the crank and closes the contact MC so that the switch machine SM may be controlled by the operator at the central office. However, the trainman may return the switch to its original position, if desired, in which case the operator does not find it necessary to move lever SML to the new position in order to gain control of the switch after the hand signalling conditions are over.

While the train is being hand signalled over the track switch TS, the track relay T is, of course, deenergized so that the lock relay L drops away. Such deenergization of the lock relay L only maintains the relay WZ deenergized inasmuch as front contact ID of relay W2 is already open. During the passage of the train over the track switch, the operator can not change the position of the relay WZ, nor can he energize it because the lock relay is deenergized. If he should move the lever SML back to its former position, the relay Z would not be in correspondence with the relay WP so that even if there were a momentary loss of shunt and the track relay T momentarily picked up, the relay L would not be picked up inasmuch as the relays Z and WP would not be in corresponding positions. If the operator moved the lever .SML to the new position in correspondence with the track switch TS, than such momentary energization of the track relay T would pick the lock relay L up, but it would do no harm inasmuch as the lock relay would be immediately dropped away upon the reestablishment ofthe train shunt and the relay WZ would remainin the same position.

From this it will be understood that each time the operator again desires to control the track switch after having allowed a train to be hand signalled over the track switch, he must move the lever SML into correspondence with the position of the track switch TS as indicated by the relay WP in order to pick up the lock relay L and again gain control of the relay WZ.

A similar condition exists when a signal has been cleared inasmuch as the lock relay L is deenergized for each clearing of the signal and is maintained deenergized so long as a signal is cleared so that the lever SML must be in correspondence with the track switch TS subsequent to the putting to stop of such signal in order to close the pick up circuit for the relay L to allow the operator to gain control of the relay WZ so that it may be operated to a new position. This feature has been conveniently termed the electric lever lock equivalent; and it is apparent that this feature applies to the present invention both under the circumstances of the clearing of a signal for the passage of trafiic over the track switch or under the condition where the operator allows a train to be hand signalled over the track switch.

Completion of an operating stroker-In the usual manipulation of the control levers of a control machine, the operator first moves the switch machine control lever SML for the track switches in the route,which he desires to set up,'to proper positions and then actuates the governing signal control lever. Such sequence of operation causes the relay WZ to be first properly positioned followed by the picking up of the relay GZ which causes the lock relay L to drop away, thereby preventing further control of the relay WZ. While the lock relay is dropped away, relay W2 is maintained energized by reason of its stick circuit. Thus, so long as the track switch is in midstroke, energy is applied to the switch machine SM through back contacts 23 and 24 of the correspondence relay RCR and NCR respectively. Thus, an operation once initiated is caused to be completed irrespective of the immediate operation of the signal control lever SGL.

If while a signal is cleared, for some reason the track switch should be jarred or moved out of a completely locked position, the relay WP would be deenergized opening front contact 2'? and deenergizing whichever correspondence relay NCR. or RCR might be picked up. This would close the back contacts 23 and 24 again applying energy to the switch machine SM inasmuch as the relay WZ would be picked up although the lock relay L would be dropped away and cause the track switch TS to be immediately restored to its fully locked former position. This feature has been conveniently termed the electrical bias which is effective under all conditions except while the central tower operator is allowing a train to be hand signalled over the track switch.

SUM MARY A system of centralized trafiic control has been provided for a railroad track switch and its signals which checks the response of the switch control relay means in such a way that the correspondence relays at the track switch actually indicate the correspondence between the track switch and its control lever for the purpose of selecting signals therethrough. The present invention further provides a feature whereby the track switch is always restored to its former position in the event that it creeps out of a fully locked position thereby providing what has been conveniently termed the electrical bias for the switch machine control, which feature, however, is employed in combination with a feature of control for hand signalling wherein such electrical bias is removed from the switch machine while a train is being hand signalled over the track switch. All of these features are provided in a most advantageous way with the feature of electric lock equivalent so that the operator must always restore his switch control lever into correspondence with the existing position of the track switch after each signal clearing or after each hand signalling situation before he can operate the track switch to a new position. Such a feature prevents the momentary loss of a shunt, while a train is passing over the track switch, from causing an erroneous operation of the track switch under such circumstances.

The system of the present invention also provides for the completion of an operating stroke of the switch machine although the locking of the switch machine becomes effective immediately following actuation of the signal control lever governing traffic over the track switch.

Although the lock relay, which looks the track switch, is dropped immediately upon the energization of the signal control relay GZ, the signal cannot be cleared during the operation of a track switch because it is necessary that the correspondence relay be picked up which does not occur until the relays WZ and WP are in correspondence. The track switch machine includes in its control circuit, back contacts of the correspondence relay, so that it is evident that a signal clearing circuit cannot be closed simultaneous or contemporaneous with the closing of the switch machine control circuit.

It is to be understood that although the present invention has been considered as applied to one specific embodiment, the principles of the present invention may be applied to various other types of control systems such as code control systems.

Having disclosed a trafiic controlling system as one specific embodiment of the present invention, it is desired to be understood that this form is selected to facilitate the disclosing of the present invention rather than to limit the number of forms which it might assume, and it is to be understood that various alterations, modifications and additions may be applied to the present invention without in any way departing from the spirit or scope of the present invention as limited by the appended claims.

What I claim is:

1. In a switch and signal control system for railroads; a power-operated track switch provided with cranking means to enable it to be hand cranked; a three-position control lever having normal and reverse controlling positions and a non-controlling position; a switch machine control relay; a lock relay; control circuit means connecting said control lever and said switch machine control relay for controlling said switch machine control relay to normal and reverse energized positions, said circuit means including a contact closed only when said lock relay is energized; stick circuit means for said switch machine control relay closed if said lock relay is deenergized and if said switch machine control relay is then energized over said control circuit means; a normally closed energizing stick circuit for said lock relay opened whenever traffic passes over said track switch, a pick-up circuit for said lock relay closed only if said control lever is in a normal or reverse position corresponding to the position then assumed by the track switch; operating circuits for said switch machine controlled by said switch machine control relay including a source of potential and effective to operate the track switch to a normal or reverse position in accordance with the normal or reverse energized position of said switch machine control relay and including contacts in each circuit opened automatically when said switch machine completes its operating stroke, said operating circuits having said potential removed therefrom while said switch machine control relay is deenergized, whereby the accidental movement of the switch machine out of a normal or a reverse position again supplies energy to the switch machine in accordance with the energized normal or reverse position of said switch machine control relay irrespective of whether said lock relay is in its attracted or retracted position, and whereby said control lever can be moved to its non-operating position to deenergize said switch machine control relay before said lock relay assumes its retracted position and prevent such application of power to said switch machine when said cranking means is to be operated, and whereby said control lever must assume or be returned into correspondence with the last energized position of said switch machine control relay subsequent to each locking of the switch machine control relay before the switch can be power operated to a new position.

2. In an interlocking system for railroads; the combination with a track switch; a signal for governing trafilc over said track switch; a track circuit including a normally energized track relay associated with said track switch; a switch machine for operating said track switch; switch control relay means which may assume a normal condition and a reverse condition; a lock relay; manually controllable contacts; pick-up circuits for controlling said switch control relay means including said manually controllable contacts and a front contact of said lock relay; stick circuits for said switch control relay means including a back contact of said lock relay; a normal operating circuit for said switch machine including a contact closed when said switch control relay means assumes the normal condition and a contact open when said switch machine assumes the normal positions; a reverse operating circuit for said switch machine including a contact closed when said switch control relay means assumes the reverse condition and a contact open when said switch machine assumes the reverse position; switch repeating contacts reflecting the position assumed by the track switch including normal contacts closed only if said track switch assumes the normal position and including reverse contacts closed only when said track switch assumes the reverse position; a normally deenergized signal clearing relay which if energized tends to clear said signal; a pick-up circuit for said lock relay closed only when said switch control relay means assumes a normal condition and said normal contacts are closed or said switch control relay means assumes a reverse condition and said reverse contacts are closed; and a stick circuit for said lock relay independent of said switch control relay means and including a front contact of said track relay and a back contact of said signal clearing relay; whereby if said signal is cleared or attempted to be cleared While said manually operable contacts are closed accidental movement of the switch machine from an extreme position will close an operating circuit for said switch machine irrespective of whether said track relay is energized or deenergized, and whereby said manually controlled contacts must be operated to a condition in correspondence with said normal and reverse contacts to close a pick-up circuit for said lock relay after each deenergization of said lock relay before said switch control relay means can be again controlled.

3. In an interlocking system for railroads; the combination with a track switch; a signal for governing trafiic over said track switch; a track circuit including a normally energized track relay associated with said track switch; a switch machine for operating said track switch; switch control relay means which may assume a normal condition and a reverse condition and an inactive condition; a lock relay; manually controllable contacts; pick-up circuits for controlling said switch control relay means including said manually controllable contacts and a front contact of said lock relay; stick circuits for said switch control relay means including a back contact of said lock relay; a normal operating circuit for said switch machine including a contact closed when said switch control relay means assumes the normal condition and a contact open when said switch machine assumes the normal position; a reverse operating circuit for said switch machine including a contact closed when said switch control relay means assumes the reverse condition and a contact open when said switch machine assumes the reverse position; switch repeating contacts reflecting the position assumed by the track switch including normal contacts closed only if said track switch assumes the normal position and including reverse contacts closed only when said track switch assumes the reverse position; a normally deenergized signal clearing relay which if energized tends to clear said signal; a signal clearing circult including a front contact of said signal clearing relay and a back contact of said lock relay, a pick-up circuit for said lock relay closed only when said switch control relay means as sumes a normal condition and said normal contacts are closed or said switch control relay means assumes a reverse condition and said reverse contacts are closed; and a stick circuit for said lock relay independent of said switch control relay means and including a front contact of said track relay and a back contact of said signal clearing relay; whereby if said signal is cleared or attempted to be cleared while said manually operable contacts are not in their inactive condition accidental movement of the switch machine from an extreme position will close an operating circuit for said switch machine irrespective of whether said track relay is energized or deenergized, and whereby said manually controlled contacts must be operated to a condition in correspondence with said normal and reverse contacts to close a pick-up circuit for said lock relay after each deenergization of said lock relay before said switch control relay means can be again controlled.

WINTHROP K. HOWE. 

